This invention relates to generally to prosthesis for continuous internal peritoneal dialysis and a method of carrying out peritoneal dialysis. More specifically, this invention relates to artificial kidneys, and more specifically to artificial kidneys implantable within a person""s body with the intent that the patient be free from constant dialysis and transplantation. The artificial kidneys of this invention cause the removal of fluids from the person""s body. For the treatment of edema states that are refractory to treatment with diuretics the dialysate can be a selected hypertonic solution for removing excess fluids; principally water.
The dialysis art is a highly developed one; providing a variety of teachings for dialyzing a patient. Related art teachings include hemodialysis, kidney transplantation, and introduction of a dialysate into a patient""s abdomen or bloodstream.
In accordance with a related dialysis procedure (e.g., hemodialysis) for purifying blood in a patient experiencing kidney failure, the contaminated blood is directed from a blood vessel of the patient""s arm through a dialyzing membrane located extracorporeally of the body, in which the blood gives up its impurities to the dialyzing fluid. The purified blood is then directed back into the patient""s body through another blood vessel. A representative disclosure of a system for use in purifying arterial blood and providing a venous return is disclosed in U.S. Pat. No. 3,579,441, issued to Brown.
The dialysis art suggests the use of related peritoneal dialysis systems wherein a dialysate is introduced directly into the abdomen of the patient and functions to receive impurities from the blood at the abdominal capillaries, and then is mechanically removed from the body. Representative peritoneal dialysis systems of this type are disclosed in U.S. Pat. No.: 4,681,564 (Landreneau); U.S. Pat. No. 4,655,762 (Rogers); U.S. Pat. No. 4,586,920 (Peabody) and U.S. Pat. No. 4,437,856 (Valli).
The absorption of dialysate into the bloodstream interferes with the peritoneum dialysate""s ability to do its job of pulling in fluids. Therefore, peritoneal dialysis relies physiologically on the fact that the dialysis fluid in the abdominal cavity is more viscous or thicker than blood. In other words, the dialysis fluid has a higher osmolality or chemical potential than the bloodstream. This difference in potential causes water and other molecules known to those skilled in the art to diffuse into the abdomen via the semi-permeable membranes of the peritoneum and mesenteric parietes which line the abdominal cavity.
The related art systems known to applicants suffer from one or more disadvantages. For example, a number of prior art systems require that the patient be connected, e.g., xe2x80x9chooked-upxe2x80x9d, to a dialysis machine. This renders the patient immobile during treatment, is expensive to administer, and subjects the patient to a high risk of infection, and even death. Patients are protein restricted, because protein yields toxic degradation products (e.g., nitrogenous wastes) largely responsible for uremia, the state of being in kidney failure. Toxic levels of potassium may also result from the treatment.
Additionally, most previous modes of dialysis have been essentially intermittent, rather than continuous; resulting in a variety of disturbances to the body""s equilibrium. Patients become either over-hydrated or under-hydrated due to the intermittent process of adding and removing fluids. The systems can not maintain proper blood volume and chemical balance beyond the few hours following the treatment. The treatments sap the patient""s energy and sense of well-being, making the patient look and feel chronically ill, and critically affecting the patient""s lifestyle, happiness and longevity.
Typically in chronic peritoneal dialysis, the dialysate is introduced directly into the peritoneal space via a catheter and removed after it has drawn in urine. Chronic contact of the peritoneum with hypertonic dialysate solutions often creates chronic peritonitis, which is a painful, dangerous condition that interferes with the peritoneal dialysis process. In fact, it should be noted that in related peritoneal dialysis, direct contact of dialysate in the peritoneal cavity creates major problems with the chronic peritoneal dialysis procedure. Peritoneal irritation and chronic thickening caused by the dialysis leads to poor diffusion and ultra filtration. Tonicity in the peritoneal cavity increases, which draws fluid back into the cavity. Reabsorption of dialysate and unconcentrated urine interferes with the process of discarding this excessive fluid.
Moreover, dialysate that is in direct contact with the peritoneal cavity interferes with the very difference in osmotic pressure needed for the whole process of diffusion and ultra filtration. Even if the dialysate molecule is inert versus the sugar, salt or albumin used in standard dialysis, each of which causes its own special problems when reabsorbed by the lymphatic system, it creates a tremendous problem with oncotic pressure. In addition, the dialysate in the peritoneal space can cause problems in the bloodstream (e.g., hypertonic sugar, hypertonic salt, increases in nitrogenous wastes, and problems in the bloodstream including bleeding and clotting disorders, poisoning various enzyme systems, antigen-antibody reactions, D-C, etc.).
With respect to transplantation, the high cost and risks are well known. A match for the patient must be found, which may take years. If a kidney is found, and the patient is still strong enough to receive it, then there is no guarantee that the kidney will be accepted. The patient""s immune system may recognize a kidney transplanted from another as foreign matter and act to combat and reject this perceived invasion. Anti-rejection medication, such as azathioprine, cyclosporine and steroids help to prevent rejection. However, anti-rejection medicines have a large number of side effects. If rejection occurs, treatment is available to possibly reverse the episode, but at the cost of more medication and side effects. With kidney transplantation, about one third of the patients do very well, about one third remain chronically ill, and about one third of the patients die within five years.
A need clearly exists for a prosthesis that is lower in cost than existing systems, that can be utilized with a minimum of risk to the patient and that provides greater freedom of movement for the patient. Therefore, it would be beneficial to provide an internal peritoneal dialysis prosthesis and method. It would also be beneficial to provide an internal peritoneal dialysis prosthesis and method which is simple in operation and requires relatively few, if any, moving parts.
One preferred embodiment of the present invention includes a prosthesis for internal peritoneal dialysis. The prosthesis comprises an abdominal sac, a subcutaneous access reservoir and a conduit. The abdominal sac is arranged to include a dialysate therein, the abdominal sac has a wall including a first semi-permeable membrane. The abdominal sac is adapted to be retained in the abdominal region of a patient""s body for receiving unconcentrated urine through the first semi-permeable membrane without permitting the dialysate to exit through the wall of the abdominal sac.
The subcutaneous access reservoir is adapted to be retained in the patient""s body substantially adjacent the patient""s skin. The subcutaneous access reservoir is in fluid communication with the abdominal sac for delivering dialysate to the abdominal sac and removing the received unconcentrated urine from the abdominal sac. The conduit provides the fluid communication between the abdominal sac and the subcutaneous access reservoir.
In this preferred embodiment, the received unconcentrated urine exits the abdominal sac through only the conduit or the first semi-permeable membrane. The abdominal sac of this preferred prosthesis may also include a main body portion and a plurality of finger portions extending therefrom. The finger portions are arranged for placement between layers of mesentery membrane to maximize the surface area of the abdominal sac between the layers.
In another preferred embodiment of the present invention, the prosthesis for internal peritoneal dialysis includes containing means, subcutaneous accessing means and passage means. The containing means is an approach for holding a dialysate therein, the containing means has a wall including a first semi-permeable membrane. The containing means is adapted to be retained in the abdominal region of a patient""s body for receiving unconcentrated urine through the first semi-permeable membrane without permitting the dialysate to exit through the wall of the containing means.
The subcutaneous accessing means is an approach for delivering dialysate to the containing means and removing the received unconcentrated urine from the containing means. The subcutaneous accessing means is adapted to be retained in the patient""s body substantially adjacent the patient""s skin, and has fluid communication with the containing means. The passage means is an approach for providing the fluid communication between the containing means and the subcutaneous accessing means.
In this preferred embodiment, the received unconcentrated urine exits the containing means through only the passage means or the wall of the containing means. The containing means of this preferred prosthesis may also include a main body portion and a plurality of finger portions extending therefrom. The finger portions are arranged for placement between layers of mesentery membrane to maximize the surface area of the abdominal sac between the layers.
The present invention, in another preferred embodiment includes a method for withdrawing unconcentrated urine from a patient. The method comprises depositing an abdominal sac, a subcutaneous access reservoir and a conduit in the abdominal region of a patient. The sac is adapted to receive a dialysate therein, and has a wall including a first semi-permeable membrane for receiving unconcentrated urine through the semi-permeable membrane without permitting the dialysate to exit through the semi-permeable membrane. The conduit provides fluid communication between the abdominal sac and the subcutaneous access reservoir for delivering dialysate to the abdominal sac and for removing the received unconcentrated urine from the abdominal sac.
This method also includes placing the subcutaneous access reservoir substantially adjacent the patient""s skin, and injecting the dialysate into the abdominal sac. The received unconcentrated urine exits the abdominal sac through only the conduit or the first semi-permeable membrane. For an abdominal sac that includes a main body portion and a plurality of finger portions extending therefrom, the method may also include the step of placing the finger portions between layers of mesentery membrane to maximize the surface area of the abdominal sac between the layers.